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Bureau of Mines Information Circular/1988 



Surface Testing and Evaluation 
of the Hopper- Feeder- Bolter 



By Robert J. Evans, William D. Mayercheck, 
and Joseph L. Saliunas 




UNITED STATES DEPARTMENT OF THE INTERIOR 




, ; ,y WCw .^MA^iU^^ 



Information Circular 9171 

iv A 



Surface Testing and Evaluation 
of the Hopper-Feeder-Bolter 



By Robert J. Evans, William D. Mayercheck, 
and Joseph L. Saliunas 



UNITED STATES DEPARTMENT OF THE INTERIOR 
Donald Paul Hodel, Secretary 

BUREAU OF MINES 

David S. Brown, Acting Director 



-fVlB* 







Library of Congress Cataloging in Publication Data: 



Evans, Robert J. 

Surface testing and evaluation of the hopper-feeder-bolter. 



(Information circular / United States Department of the Interior, Bureau of Mines ; 9171 ) 

Bibliography. 

Supt. of Docs, no.: I 28.27: 9171. 

1. Coal-mining machinery— Testing. I. Mayercheck, William D. II. Saliunas, Joseph 
L. III. Title. IV. Title: Hopper-feeder-bolter. V. Series: Information circular (United States. 
Bureau of Mines) ; 9 1 7 1 . 

TN295.U4 622 s [622 '.334 '028] 87-600300 



CONTENTS 

Page 

Abstract 1 

Introduction 2 

Description of the HFB 3 

Power and control 4 

Chassis 6 

Bolter module 6 

Surface testing 8 

Test-program overview 8 

Initial checkout 8 

Maneuverability 8 

Roof-bolter evaluation 9 

Place change with roof bolting 11 

Place-change time study 13 

Rock breaking 14 

Tail-boom lifting 16 

Coal conveying 16 

Dust-collector evaluation 19 

Drawbar pull 20 

TRS load measurement 21 

Noise survey 23 

Li ght survey 25 

Shuttle-car loading trial 26 

Surface test summary 27 

Repairs and modifications 29 

Mining plans 29 

HFB with two-pass continuous miner 29 

Bolter-module hazard analyses 33 

HFB with continuous haulage 34 

Conclusions 35 

Appendix A. — HFB deployment 36 

Appendix B. — HFB modification summary 37 

Appendix C. — HFB repair summary 39 

ILLUSTRATIONS 

1. HFB overall view * 3 

2. Bolter module 3 

3. General arrangement of the HFB 4 

4. Radio remote control 6 

5. HFB outby end view 7 

6. Bolting in the MBTS 9 

7. Bolter-module stability trial 11 

8. Rock-breaking trials 15 

9. Breaker-motor's power consumption 15 

10. Tail-boom lifting trials 16 

11. Coal-conveying trial configuration 17 

12. Relocated dust boxes 19 

13. Drawbar pull test 21 

14. TRS cylinder cross section 22 

15. TRS load measurement test configuration 22 

16. Typical sound-level data sheet 24 

17. Right- and left-side passby noise spectrum 25 

18. Top incident light measurements for the hopper feeder 26 



11 



ILLUSTRATIONS— Continued 

Page 

19. Top incident light measurements for the bolter 26 

20. Incident light measurements for the bolter sides 26 

21. Incident light measurements for the bolter front and rear 26 

22. HFB shuttle-car loading trial 28 

23. Spillage during loading trial 28 

24. Face-equipment configuration for 10-ft cuts 29 

25. Mining plan for 20-ft cuts 31 

26. Bolter module positioned for LH miner cut 32 

27. Bolter module positioned for RH miner cut 32 

28. HFB operator's areas 33 

29. Hopper feeder 34 

30. Hopper feeder used with MBC 35 

31. Hopper feeder MBC interface 35 

32. HFB with continuous haulage 35 

A-l. HFB deployment 36 

TABLES 

1. HFB specifications 5 

2. Roof-bolter time-study data 10 

3. Detailed description of HFB operations 12 

4. Place change with roof-bolting time-study summary, minutes and seconds... 13 

5. Coal-conveying trial summary 17 

6. Coal-conveying trial breakdown log 18 

7. Dust-collector airflow measurements 20 

8. TRS load-test summary 23 

9 . HFB mining rates 30 





UNIT OF MEASURE ABBREVIATIONS USED 


IN THIS REPORT 


dc 


direct current 


in 3 


cubic inch 


dB 


decibel 


in/s 


inch per second 


dBA 


decibel, A-weighted 


kHz 


kilohertz 


°F 


degree Fahrenheit 


kW 


kilowatt 


fc 


f ootcandle 


lb 


pound 


fL 


f ootlambert 


lb/ft 3 


pound per cubic foot 


ft 


foot 


m 


meter 


ft 3 


cubic foot 


min 


minute 


ft 3 /min 


cubic foot per minute 


pet 


percent 


ft* lb 


foot per pound 


psi 


pound per square inch 


ff lbf 


foot pound (force) 


r/min 


revolution per minute 


f t/min 


foot per minute 


s 


second 


gal 


gallon 


St 


short ton 


h 


hour 


st/min 


short ton per minute 


hp 


horsepower 


V ac 


volt, alternating current 


Hz 


hertz 


V dc 


volt, direct current 


in 


inch 







SURFACE TESTING AND EVALUATION 
OF THE HOPPER-FEEDER-BOLTER 

By Robert J. Evans, 1 William D. Mayercheck, 2 and Joseph L. Saliunas 3 



ABSTRACT 

The Hopper-Feeder-Bolter (HFB) is a prototype multifunctional machine 
designed to improve productivity by minimizing continuous miner place 
changes. It is designed primarily to work beside a two-pass continuous 
miner, bolting on one side and then place changing to bolt the other 
side while simultaneously providing a surge car and lump breaker located 
directly behind the continuous miner. 

Surface testing was conducted at the Bureau of Mines Mine Equipment 
Test Facility (METF) to evaluate overall system performance and relia- 
bility. Tests were conducted to evaluate place changing, tramming, lump 
breaking, roof bolting, drawbar pull, conveying, temporary roof-support 
(TRS) capacity, lighting, and noise. Surface test results indicate the 
HFB is ready to be tested and evaluated underground in a production 
mode. 



Civil engineer, Pittsburgh Research Center, Bureau of Mines, Pittsburgh, PA. 
■^Supervisory physical scientist, Pittsburgh Research Center. 
^Project engineer, Boeing Services International, Pittsburgh, PA. 



INTRODUCTION 



The HFB is a prototype multifunctional 
mining machine that was conceived by the 
Bureau of Mines and designed and fabri- 
cated by the Engineered System and Devel- 
opment Corporation under a Bureau con- 
tract. This machine combines functions 
typically performed by a roof bolter and 
a feeder-breaker. It addresses a variety 
of problems that limit productivity of 
room-and-pillar mining systems: 

The maximum instantaneous output of a 
continuous miner is typically greater 
than the instantaneous haulage rate of 
the outby continuous haulage system. The 
HFB provides compatible surge capacity 
for the continuous miner output and 
levels out the coal-rock input for the 
continuous haulage system. 

Production delays occur when large 
pieces of coal or rock must be broken 
manually before being transported through 
a continuous haulage system. The HFB 
provides an onboard lump breaker. 

Production time is lost when a continu- 
ous miner and roof bolter place change. 
Because the HFB can bolt beside the con- 
tinuous miner, the number of entry-to- 
entry place changes is decreased; entry- 
to-entry place changes are replaced with 
side-to-side equipment changes in place. 
A continuous mining system using the HFB 
has some of the productivity advantages 
of a miner-bolter without the high capi- 
tal costs. 

The HFB can be used in various min- 
ing plans with several face equipment 
schemes. It can be used with or without 
the optional bolter module, and it can 
load into a continuous or intermittent 
(shuttle-car) haulage system. 

Scott, F. E. New Technology Improves 
Roof Control Safety. Coal Mining, v. 22, 
No. 8, Aug. 1985, pp. 24-28. 

Chironis, N. P. Bureau Continues to 
Pour Out Useful Medley of Machines and 
Ideas. Coal Age, v. 21, No. 2, Feb. 
1986, pp. 22-35. 



Because of the many novel features of 
the HFB, an extensive surface test eval- 
uation program was conducted at the 
Bureau's METF prior to an in-mine trial. 
The objectives of the surface testing and 
evaluation program were 

1. To "shake down" the HFB and improve 
performance and reliability based upon 
observations made under simulated under- 
ground conditions; 

2. To measure HFB performance criteria 
so that underground performance and oper- 
ating requirements could be predicted; 

3. To determine if the HFB meets its 
design criteria and is worthy of an 
in-mine trial; and 

4. To prepare the HFB for an in-mine 
trial, including electrical approval by 
the Mine Safety and Health Administration 
(MSHA). 

The principal advantages of surface 
testing prior to an in-mine trial are 
that equipment performance can be proven 
and improved upon without interfering 
with production at an operating mine; 
this is absolutely paramount with face 
equipment such as the HFB. Even though 
the HFB has potential advantages, most 
mines would not risk the installation 
and operation of unproven face equipment, 
since any failure would be expensive in 
terms of operating cost and lost produc- 
tion. Because of this risk, there is a 
strong tendency in the mining industry to 
resist the introduction of novel mining 
systems or to reject very promising sys- 
tems after a short term if the in-mine 
trial does not meet anticipated results. 
Even though the most rigorous surface 
test and evaluation program will not sub- 
ject equipment to all of the harsh con- 
ditions found in the underground mines, 
a surface test program significantly 
increases the probability that problems 
related to major design deficiencies will 
be eliminated prior to the initial under- 
ground trial. 



DESCRIPTION OF THE HFB 

The HFB (fig. 1) consists of a crawler- connected to the chassis by a telescoping 
mounted chassis and a crawler -mounted boom. The chassis has the capacity to 
bolter-module assembly (fig. 2) that is level out miner coal-rock surges from 12 




FIGURE 1.— HFB overall view. 




FIGURE 2.— Bolter module. 



to 7 st/min. An onboard lump breaker 
crushes against a universal chain convey- 
or. The conveyor on the outby end has a 
45° heavy-duty swing tail that transports 
coal to the next stage of haulage. The 
bolter is connected to the HFB chassis by 
a telescoping boom and contains two mast- 
type bolter assemblies. Specifications 
for the HFB are presented in table 1. 
Figure 3 shows the components of the HFB. 

POWER AND CONTROL 

The HFB requires three-phase 460-V ac 
power, which runs four electric motors: 
a 75-hp 460-V ac motor for the lump 
breaker; two 21-hp 220-V dc motors for 
tramming; and a 160-hp, 460-V ac motor to 
drive a single variable-displacement hy- 
draulic pump and four fixed-displacement 
hydraulic pumps. The direct-current (dc) 
tram motors of the HFB chassis are con- 
trolled by a solid-state control system 



using silicon-controlled rectifiers (SCR) 
to convert the alternating current (ac) 
to dc power. Use of SCR's also permits 
variable speed control of the tram 
motors, allowing a tram speed of to 90 
ft/min. Hydraulic power is used for all 
functions other than breaker operation 
and tramming the main HFB chassis. A 
100-gal-capacity hydraulic reservoir is 
located on the right side of the main 
chassis. Dust-suppression water can be 
circulated through the hydraulic reser- 
voir heat exchanger to cool the oil. 
Electrical control components are located 
in a single, explosion-proof control box 
located on the left side of the chassis. 
Intrinsically safe solenoid valves con- 
trol all hydraulic actuators except the 
bolting functions and conveyor drive. 
Five emergency-stop ribbon switches are 
located on the chassis and four are 
located on the bolter module. 



Optionol bolter-module assembly 



Boom traverse ^Main control panel 

drive motor Pump motor / ^Hydraulic reservoir 

Secondary dust-collector r 
" box and vacuum Dumo /~ ^ onve y° r 
motor 




2-drill-head 
roof bolter 



motor 



Conveyor 
elevation cylinders 



Crossover 



PLAN 



Breaker motor 



TRS 
cylinders ->sz 



Breaker 
speed reducer 




maximum extension 

ELEVATION 
FIGURE 3.— General arrangement of the HFB. 



Not to scale 



TABLE 1. - HFB specifications 

HFB 48 ft, 8 in long with fully extended boom. 

54-in minimum working heights. 

Chassis 460-V ac power. 

4 ft high; 9 ft, 7 in wide; 26 ft, 9 in long. 

Weight - 49,500 lb. '" 

Mounted on 2 16- by 84-in crawler tracks. 

2 tram motors at 21 hp, 220 V dc. 

Tram motors SCR controlled for to 90 ft/min tram speed. 

1 breaker motor at 75 hp, 460 V ac. 

1 pump motor at 100 hp , 460 V ac. 
191-ft -capacity hopper. 

30 in wide, variable speed and direction, center-strand chain 

conveyor. 
Variable elevation tail boom. 
Variable swing tail boom (45° to the left and right of 

centerline) . 
Radio remote control. 

Bolter module Hydraulic and intrinsically safe power provided by chassis. 

Height varies from 4 ft (TRS retracted) to 8 ft (TRS fully 

extended) . 
5-ft, 5-in boom extension capability. 
Weight - 7,000 lb. 

Mounted on a single, 11- by 36-in crawler track. 
TRS exerts loads of 12,000 lb at 500 psi. 

2 drill heads on 4-ft spacing. 

Drill torque adjustable to 275 fflbf at 2,000 psi. 
Drill speed adjustable to 325 r/min. 
Drill thrust adjustable to 7,000 lb. 
3-stage vacuum dust-collection system. 

Safety 9 emergency stop switches (5 on the chassis, 4 on the bolter 

module). 
Fire-suppression water sprays. 
Dust-suppression water sprays. 

Components Undercarriage and tram motors from Joy 14 BU loader. 

Reliance pump and breaker motors. 

FMC solid-state tram control system. 

Faulk breaker speed reducer. 

Fletcher drill boxes. 

Donaldson dust-collection system. 

Joy conveyor chain. 

Eaton and commercial shearing pumps. 

McJunkin lights. 



The HFB chassis can be operated from 
two locations: the control panel on the 
machine, and the remote control. The 
main control panel, consisting of a sin- 
gle row of toggle switches, located on 
the right side of the HFB, can be used 
to operate all functions except roof 
bolting. The remote-control unit (fig. 
4) can be used to operate all major HFB 
functions except bolting. The frequency 
modulation (FM), a radio remote con- 
trol, is powered by a specially modified 
12-V dc cap-lamp battery. A radio re- 
ceiver is located in the controller box. 
Bolter-module controls are located on the 
inby edge of the bolter-module's bolt 
tray. 

CHASSIS 

The main HFB chassis is mounted on two 
crawler tracks: each crawler is 16 in 
wide by 84 in long. A 30-in-wide center- 
strand chain conveyor runs the full 
length of the HFB chassis (fig. 5). A 
4-3/4-st-capacity surge hopper is located 
on the front portion of the chassis. The 
chain conveyor is powered by a variable- 
displacement hydraulic motor located on 
the conveyor tail boom, which permits 
variable conveyor speed from to 200 
ft/min in both directions. The conveyor 
speed can be controlled in manual and 
automatic (anti-stall) modes. A hand- 
operated lever is used for manual speed 
and direction control. An anti-stall 
switch is used to automatically control 
the conveyor speed. In the automatic 
anti-install mode, the conveyor speed is 
decreased when the breaker motor draws 
large amounts of current. The conveyor 
tail boom can pivot 42 in. in both direc- 
tions from the chassis centerline. 
It has elevating cylinders and was 
designed to support and position the inby 
end of the continuous haulage system. 

The coal-rock lump breaker is located 
in the center of the HFB chassis over the 
chain conveyor. It consists of rows of 
carbide-tipped conical bits mounted on 
a shaft that rotates at 90 r/min. A 
double-strand roller chain connects the 
breaker shaft to a gear speed reducer 
driven by the 75-hp breaker motor. 




FIGURE 4.— Radio remote control. 

Six 480-V ac sodium vapor lamps are 
located on the HFB chassis. A single, 
intrinsically safe fluorescent lamp is 
located on the inby end of the bolter 
module. 

BOLTER MODULE 

The bolter module is connected to the 
HFB chassis by means of a nonpowered 
telescoping boom. The bolter module con- 
tains two mast-type bolter assemblies on 
each side of the machine, two sets 
of bolter operator controls, two TRS cyl- 
inders, two primary dust-collector boxes, 
and a single, hydraulically driven 11- 
in-wide by 36-in-long crawler track. A 
rotary actuator, located between the 
operator controls, is capable of rotating 
the entire bolter module about the end of 
the telescoping boom. A gooseneck in the 
boom, directly behind the bolter module, 




FIGURE 5.— HFB outby end view. 



enables bolter operators to cross over 
the boom. A single tilt cylinder, lo- 
cated between the bolter module and the 
boom assembly, controls the sideways tilt 
of the bolter module. The telescoping 
boom is 7 ft, 7 in long when retracted 



and is capable of extending to 13 ft. 
The boom is attached to the HFB chas- 
sis by a movable sliding bracket, which 
allows the end of the boom to be located 
at different positions along the inby end 
of the chassis. 



SURFACE TESTING 



TEST-PROGRAM OVERVIEW 

Surface tests were divided into 
sequences that evaluate a particular sub- 
system or machine function to verify 
and measure the performance of the HFB. 
Numerous modifications were made to the 
HFB during the test program to cor- 
rect deficiencies noted during surface 
testing. Important test sequences were 
recorded on videotapes that are available 
at the Pittsburgh Research Center (PRC). 

INITIAL CHECKOUT 

The assembled HFB was delivered to 
the METF on April 19, 1983. All safety 
devices and functions were checked for 
proper operation, and several minor 
repairs, adjustments, and modifications 
were made; all function rates were mea- 
sured at or close to specifications. 

MANEUVERABILITY 

This first test sequence was conducted 
to measure the HFB tram rate on a dirt 
floor, along with evaluation of the 
radio-control capability to determine if 
the HFB could tram with the bolter module 
in the extended position. 

Time-measured trials were made for the 
HFB to tram through a 48-ft-long entry, 
turn through a 90° intersection, and tram 
through a 48-ft-long crosscut (110 ft 
total). The entry and crosscuts were 
both 20 ft wide with 90° square corners. 
The HFB operator, using the handheld, 
remote-control unit was able to position 
himself for optimum safety and visibility 
during the trials. A single cablehandler 
was used when required. For the first 
set of maneuverability tests, a pin was 
installed into the telescoping boom so 
that the boom length was kept constant 



at 7-1/2 ft. For the second set of 
maneuverability tests, the pin was 
removed from the boom so that the boom 
was free to telescope between 7-1/2 and 
13 ft. Four trials were conducted for 
each of the two configurations. The 
average tram time required for both tram- 
ming configurations (fixed or variable 
boom length) was 1 min, 25 s; therefore, 
neither tramming configuration was supe- 
rior. The average tram speed during 
these trials was 77 ft/min, which is less 
than the specified 90 ft/min tram speed; 
this is attributed to the slower tram 
rate during the turn into the crosscut 
and can be compared with the average con- 
tinuous miner place-change tram speed of 
35 ft/min. 

Maneuverability trials were attempted 
with the bolter module in the stored 
position on the HFB. For these trials, 
the pin in the sliding bracket was 
removed and the tram drive of the bolter 
module was used to push the telescoping 
boom through the sliding bracket and into 
the hopper of the stationary HFB. The 
boom hold-down bracket was lowered onto 
the boom in an attempt to pick the bolter 
module off the ground; however, the 
bolter module was too heavy. When this 
was tried, the rear portion of the main 
chassis crawler tracks came off the 
ground. The hold-down bracket was sub- 
sequently removed from the HFB, since it 
did not function properly and tramming 
trials showed that it was not required. 

The HFB was originally equipped with a 
hold-down bracket that could store the 
bolter module clear of the ground. 

The handheld remote-control unit, which 
allows the operator to be in a safe 
position, proved easy to use enabling 
operators to quickly become adept in 
maneuvering the HFB. 



ROOF-BOLTER EVALUATION 

Roof-drilling trials were conducted to 
verify proper performance of the bolting 
system. The drilling-rate parameters for 
both bolter units were 

the drill cylinder thrust relief valve 
was set at 1,000 psi; 

the drill motor's torque relief valve 
was set at 1,850 psi; 

the unloaded drill rotation rate was 
set at the maximum rate of 1,850 r/min; 

the unloaded drilling thrust rate was 
set at 1 in/s. 

The miner bolter test structure (MBTS) 
was utilized to support two simulated 
roof blocks that were used during the 
roof-bolting trials. The bottom of the 
roof blocks were 6 ft above ground, and 
each roof block was 4 ft wide by 6 ft 
long by 6 ft high. The blocks were 
constructed from a concrete mixture of 
50 pet crushed limestone (3/4-in by 0), 
30 pet coarse sand, and 20 pet portland 



cement. The average compressive strength 
of four cylinder samples after 28 days 
was 5,100 psi. 

Mechanical expansion shell roof bolts, 
42-in long and 5/8-in diam, were used 
during the bolter evaluation; 4-in roof 
plates were used instead of 6-in roof 
plates in order to save roof block space. 
A single, 48-in-long starter steel with 
1-1/8-in-square end was used to drill all 
holes. Carbide-tipped drill bits were 
used to drill 1-3/8-in-diam holes. Both 
36- and 24-in-long drill steel wrenches 
were used to tighten the roof bolts. 

A stopwatch was used to continuously 
record the starting and stopping times 
for each drill unit. For 44 trials, 
a 24-in-deep by 1-3/8-in-diam hole was 
drilled. The vacuum dust-collection 
boxes located on the bolter module were 
emptied as required during these tests, 
and the hydraulic tank temperature was 
recorded when the dust boxes were emp- 
tied. Figure 6 shows the HFB bolting 
into the MBTS roof blocks. 

Table 2 shows the results of the roof- 
drilling trials. For 48 ft of drilling, 
the left bolter had an average drilling 
rate of 2 ft in 56 s (2.14 ft/min); for 







*-:!^ 



FIGURE 6.— Bolting in the MBTS. 



10 



TABLE 2. - Roof-bolter time-study data, minutes and seconds 





Left bolter 


Right bolter 


Oil 


Test 


Start 


Stop 


Elapsed 
time 


Start 


Stop 


Elasped 
time 


temp , 
°F 


1 

2 


1:15 

3:48 

6:45 

8:52 

32:37 

34:55 

NA 

45:56 

NA 

0:00 

2:35 

5:20 

7:16 

9:32 

13:16 

15:05 

16:37 

0:00 

2:49 

4:42 

8:15 

12:24 

0:00 

1:57 

6:01 

7:52 


2:05 

4:37 

7:32 

9:37 

33:19 

35:36 

NA 

46:41 

NA 

1:20 

3:42 

6:16 

8:05 

10:24 

14:02 

15:50 

17:25 

1:19 

4:03 

5:53 

9:18 

13:14 

1:10 

3:00 

6:51 

8:42 


0:50 
0:49 
0:47 
0:45 
0:42 
0:41 

NA 
0:45 

NA 
1:20 
1:07 
0:56 
0:49 
0:52 
0:46 
0:43 
0:48 
1:19 
1:14 
1:11 
1:03 
1:10 
1:10 
1:03 
0:50 
0:50 


1:27 

3:40 

NA 

8:44 

32:42 

35:00 

38:45 

46:02 

48:28 

2:06 

5:09 

6:58 

NA 

12:55 

NA 

16:30 

19:25 

NA 

2:49 

4:42 

8:27 

12:24 

0:06 

4:06 

6:01 

7:52 


2:15 

4:25 

NA 

9:29 

33:30 

35:50 

39:32 

46:48 

49:16 

2:58 

6:02 

7:49 

NA 

13:42 

NA 

17:20 

20:23 

NA 

3:44 

5:42 

9:11 

13:05 

0:47 

4:48 

6:44 

8:35 


0:48 
0:45 

NA 
0:45 
0:48 
0:50 
0:47 
0:46 
0:48 
0:52 
0:53 
0:51 

NA 
0:47 

NA 
0:50 
0:58 

NA 
0:55 
1:00 
0:44 
0:41 
0:41 
0:42 
0:43 
0:43 


90° 

NA 


3 


NA 


4 


115° 


5 

6 


95° 
( 1 ) 


7 


( 2 ) 

NA 


8 


9 

10 


115° 
60° 


11 

12 

13 

14 


NA 
NA 
NA 
NA 


15 

16 

17 

18 


NA 

NA 

125° 

80° 


19 

20 

21 

22 

23 


NA 
NA 

( 2 ) 

110° 
90° 


24 

25 


NA 
NA 


26 


115° 




NAp 


NAp 


0:56 


NAp 


NAp 


0:48 


NAp 



NA Not available. 
NAp Not applicable. 



'10/1 
2 



-Re pi 



3 tests. 

ace right bit. 



NOTE. —Drill depth was 2 ft. 



44 ft of drilling, the right bolter had 
an average rate of 2 ft in 48 s (2.5 ft/ 
min). The difference in the drilling 
rates was assumed to be caused by small 
changes in the drilling parameters, such 
as relief-valve settings and flow rates 
between the left and right modules. The 
faster drilling rate observed for the 
right bolter also resulted in a higher 
bit failure rate. The carbide-tipped bit 
had to be replaced twice for the right 
bolter because of carbide chipping; 
whereas, the left bolter used the same 
bit for all trials. As the hydraulic oil 
temperature increased, both right and 
left bolters showed an increased drilling 
rate. 



Table 2 also shows when the dust boxes 
were emptied. In most cases, they were 
emptied because of test startup conve- 
nience, except in the third sequence when 
the dust collectors were full. Each of 
the two primary dust-collection boxes 
on the bolter module had a volume of 680 
in 3 , for a total volume of 1,360 in . 
The secondary dust-collection box and 
final filter were located on the HFB 
chassis approximately 35 ft away from the 
primary boxes; therefore, most cuttings 
were deposited in the two primary boxes. 
The exact number of feet to be drilled 
before emptying the primary dust boxes 
would depend on the swell factor of the 



11 



roof material being drilled. During the 
bolting trials, 24-in-deep by 1-3/8-in- 
diam holes were drilled for a total vol- 
ume of 35.6 in of in situ rock per hole. 
Up to 14 of the 24-in-deep holes were 
drilled without emptying the primary 
boxes, for a total volume of 500 in of 
in situ rock. The primary dust boxes 
were filled after the 14 holes were 
drilled, so the capacity of the primary 
boxes was approximately 28 lineal ft if a 
1-3/8-in-diam bit was used. 

The bolter module was easily posi- 
tioned at the desired location by using 
toggle-switch-controlled solenoid valves. 
Instability of the bolter module was 
observed while tramming on uneven bottom 
conditions (fig. 7). Use of the bolter 
roll cylinder allowed the bolter module 
to stabilize prior to drilling. 



PLACE CHANGE WITH ROOF BOLTING 

Time studies utilizing place changes 
with roof bolting were conducted to study 
person-machine configurations and to 
gather time-study data. Time studies 
also provide mining-rate data for mine 
operators so that they can predict min- 
ing rates for their own operation. For 
these studies, the HFB chassis was 
located in the center of the 20-ft-wide 
entry formed by the MBTS. A Jeffrey 101 
two-pass continuous miner was located 
inby of the HFB at one side of the entry. 
The HFB bolter module was located at the 
other side of the entry beside the con- 
tinuous miner. The movable roof cart of 
the MBTS was initially centered 10 ft 
behind the cutterhead of the continu- 
ous miner. During the trials, both HFB 




FIGURE 7.— Bolter-module stability trial. 



12 



bolter operators were able to drill and Drill and install two roof bolts; 

insert roof bolts into the roof blocks 

contained by the movable roof cart (fig. Tram the HFB chassis and bolter module 

6). After several practice sessions, outby of the continuous miner; 

four HFB continuous-time studies were 

conducted with the following sequence, Switch the bolter module from one side 

which simulated a 12-ft face advance: of the entry to the other; and, 

Drill and install two roof bolts; Tram the HFB chassis and bolter module 

inby and repeat. 
Advance the bolter module 4 ft using 
local control; Definitions for the time-study events 

are given in table 3. Several sequences 
Drill and install two roof bolts; were videotaped for further analysis in 

the place-change time study. 
Advance the bolter module and HFB chas- 
sis 4 ft using local and remote controls; 

TABLE 3. - Detailed description of HFB operations 

Drill and bolt: 

Start First HFB operator starts drilling. 

Event Enough time for both inside and outside HFB drill opera- 
tors to each drill a 43-in deep by 1-3/8-in-diam hole 
using a two-piece drill steel and insert and torque a 
42-in-long point anchor mechanical roof bolt. 

Stop Last HFB operator stops torquing roof bolt. 

Advance bolter module: 

Start Last HFB operator stops torquing roof bolt. 

Event Enough time to lower the TRS; advance the bolter module 

4 ft from local position, position the bolter module, 
and set the TRS. 

Stop First HFB operator starts drilling. 

Advance bolter and chassis: 

Start Last HFB operator stops torquing roof bolt. 

Event Enough time to lower the TRS, advance the HFB chassis 

8 ft using the remote control, position the bolter 
module, and set the TRS. 

Stop First HFB operator starts drilling. 

Place change: 

Start Last HFB operator stops torquing roof bolt. 

Event Enough time to lower the TRS, tram the bolter module 

outby of the miner, switch bolter-module boom to the 
opposite side, empty the dust box, tram the HFB inby 
to behind the miner, position the bolter module, and 
set the TRS. 

Stop Stop when TRS is set. 



13 



Four operating personnel were used dur- 
ing these tests: a miner operator, a 
miner helper, an "inside" bolter opera- 
tor, and an "outside" bolter operator. 
In addition, a roof-cart operator was 
used to advance the roof-cart position by 
4-ft increments to obtain a realistic 
advancing bolt pattern. The continuous 
miner was also advanced with the roof 
cart, so the cutterhead of the miner was 
always 10 ft in front of the bolter- 
module drill centerline. Both the miner 
and HFB power cables for these trials 
were located along the right side of the 
MBTS. When the miner was on the left 
side of the entry and the bolter module 
was on the right side, the miner power 
cable was tied to the mine roof (roof 
cart) with wire ties. 

The roof-bolter operators used a two- 
piece drill steel with 1-3/8-in-diam 
carbide-tipped bits. For all holes, the 
operators set the TRS , drilled 43-in- 
deep holes, inserted a 42-in-long point 
anchor mechanical roof bolt, torqued the 
bolt to 150 ff lb, and lowered the TRS. 

A 24-ft total face advance was sim- 
ulated by drilling and inserting 24 
roof bolts in a 4- by 4-ft bolt center 
pattern, as the HFB bolted beside and 
exchanged positions "in place" with 
a two-pass continuous miner. A 12-ft 
advance was made by the miner before 
changing positions with the bolter mod- 
ule. Table 4 is a summary of the time- 
study results. The time-study events 
were broken down into elements that could 
be recombined into different combinations 
to simulate different cut plans. 



Twelve "drill-and-bolt" events were 
timed for an average value of 3 min, 
12 s. The drill-and-bolt times will 
change from mine to mine, depending on 
the type and length of bolts used and the 
drilling rate. The average time deter- 
mined for these trials is valid only 
for these unique drilling conditions. 
Four "advance-bolter-module" events were 
timed for an average of 1 min, 43 s. 
Four "advance-bolt er-module-and-chass is" 
events were timed for an average of 2 
min, 44 s. Further place-change trials 
indicated that this event would not be 
part of the normal mining sequence, since 
the miner helper needs to continuously 
advance the HFB's chassis during bolting 
to keep the HFB's hopper under the miner 
tail boom. The bolter operators, there- 
fore, do not need to advance the HFB as a 
separate operation. Three place-change 
events were timed for an average value of 
5 min, 21 s. This value was decreased in 
subsequent place-change time-study tri- 
als, after an improved person-machine 
movement scheme was used. 

PLACE-CHANGE TIME STUDY 

Based upon an analysis of the videotape 
from early place-change trials, a person- 
machine movement plan for a face area 
change was established. This plan, shown 
in appendix A, was used for six trials to 
accurately determine the time required 
for the HFB bolter module to exchange 
places in a 20-ft-wide entry with a two- 
pass continuous miner. Four operating 
personnel were used: a miner operator, 



TABLE 4. - Place change with roof -bolting time-study summary, 
minutes and seconds 



Event 


Trial 1, 1 
8/23 


Trial 2, 2 
8/23 


Trial 3, ' 
8/23 


Trial 4, ' 
9/7 


Average 




3:21 
1:59 
2:40 
1:55 
3:00 
4:45 


3:04 
1:51 
2:58 
3:07 
3:20 
5:05 


2:37 
2:00 
2:15 
4:05 
4:27 
NA 


3:07 
1:01 
3:56 
1:50 
3:37 
6:12 


3:02 




1:43 




2:57 




2:44 
3:36 




5:21 




17:40 


19:25 


NAp 


19:43 


19:23 



NA Not available. 
NAp Not applicable. 



Bolter module on right, 
2 Bolter module on left. 



14 



a miner helper, the inside bolt operator, 
and the outside bolter operator. During 
the time study, time was started when the 
bolter module TRS lost contact with the 
roof during lowering. Time was stopped 
when the TRS was set against the roof 
after the place change was completed. No 
face advance was made by the bolter mod- 
ule during these studies; the final posi- 
tion of the bolter module was the same 
distance as the initial position was inby 
into the entry. 

The average time required to have the 
bolter module exchange positions in the 
entry with the continuous miner was 2 
min, 57 s for three right-to-left moves 
by the bolter module, and 3 min, 21 s for 
three left-to-right moves. The differ- 
ence in these times was attributed to the 
delay of hanging the miner cable during 
the left-to-right bolter-module move. 
The average time for both right-to-left 
and left-to-right moves was 3 min, 9 s. 

The sequence of person-machine movement 
for the place-change time-study trials is 
presented in appendix A. This sequence 
could be used for any intermittent outby 
haulage method, such as shuttle cars. A 
modification to this sequence would be 
required for use with a continuous outby 
haulage system. The sequence was de- 
signed to achieve the following objec- 
tives: (1) keep personnel from entering 
under unsupported roof; (2) keep person- 
nel from passing between moving equipment 
and the mine rib; (3) keep the bolter 
module at least 10 ft from the miner cut- 
terhead; and (4) keep the HFB hopper as 
close as possible to the miner discharge 
boom. 

ROCK BREAKING 

Rock-breaking trials were conducted to 
verify proper functioning of the breaker 
and to record the power consumption 
of the 75-hp breaker motor during rock- 
breaking operations. Rock samples used 
during the rock-breaking trial were 
competent limestone obtained from the 
Bureau's Lake Lynn Experimental Mine. 



The power consumption of the HFB was 
monitored utilizing a current transformer 
(C/T) with a ratio of 300:5 on the A and 
C phases of the HFB power cable. The 
C/T's, having a factory-stated accuracy 
of ±1 pet, were connected to a watt 
transducer that provided a 0- to 10-V dc 
output for a 0- to 240-kW power span. 
The watt transducers had a stated accu- 
racy of ±0.25 pet. 

Several different test sequences were 
conducted : 

During trial A, several small rocks 
(8- by 10- by 12-in; 8- by 18- by 8-in; 
and 6- by 16- by 10-in) were dropped 
together into the HFB hopper. The con- 
veyor motor was operated at full-speed, 
anti-stall mode and breaker motor power 
consumption was recorded during rock- 
breaking operations. 

During trial 5, a single 18- by 30- by 
24-in boulder was dropped into the HFB 
hopper. The conveyor motor was operated 
at full-speed, manual mode, and the 
breaker motor power consumption was 
recorded. The conveyor speed was varied 
by the operator during this sequence. 

During trial C, a 24- by 16- by 18-in 
rock and a 12- by 12-in rock were dropped 
together into the HFB hopper. The con- 
veyor motor was operated at full-speed, 
anti-stall mode, and the breaker motor 
power consumption was recorded. 

The HFB successfully broke all rock 
specimens during the rock-breaking tri- 
als. The breaker contained two rows of 
three conical bits mounted on a 5-in- 
diam solid shaft (fig. 8). Power to the 
breaker was transmitted from a 75-hp 
electric drive motor through a speed- 
reducer and roller-chain drive. Figure 9 
identifies plots of the breaker motor 
power consumption during the three rock- 
breaking trials. During trial A, the 
plus 6-in rocks were quickly fed through 
the breaker. The maximum observed 
power consumption was a peak of 32 kW. 



15 




:;:.. 




FIGURE 8.— Rock-breaking trials. 



80 
64 
48 
32 
16 



i i i i — i i i i — i — r~r- 1 — i — i— i — r 

—Start motor T . . . 

Trial A 



~\ — n — n — r - r 



i liVJ i 



Finish breaking 



i 



80 
64 



Q- 

§ 32 

o 16 



t — |— i— i — i — i i i i i i i — i — r— n — n—i — i — i — |— i — n — m — i i i i — r 
Trial B Breaker tripped 



Reverse 

conveyor 



i i i i i i i i i i i i 



[ I .1 I JL.i .. I..I I ill-i.. > .. .1 

I I I I l l l I I I I I I I I I I I I I 



i i i \. 



80 
64 
48 
32 
16 



-Start 
motor 



jyimJ-JjjJJiUl 



i i i i i i i — i i i i i 
Trial C 



—Finish 
breaking 



i i I i i i i i i i 



TIME, min - - 
FIGURE 9.— Breaker-motor's power consumption. 



During trial B, the bits gradually- 
chipped away at the face of a plus 18-in 
rock until the rock caught under the 
bits and the circuit breaker controlling 
the breaker motor tripped. The breaker 
was reset and the rock was eventually 
broken. During trial 5, the conveyor 
speed and direction were manually con- 
trolled, and for a portion of the tri- 
al, the rock was reversed away from 
the breaker. The power-consumption plot 
of trial B reflects this no-load condi- 
tion with a power draw 
were several instances 
when the power draw went off scale above 
80 kW. During trial C, power consump- 
tion went off scale four times, but the 
two plus 12-in rocks were broken without 
difficulty. 



of 8 kW. There 
during trial B 



16 



A unique feature of the HFB is the 
current transformer connection to the 
breaker motor power lead. A high-current 
draw on the breaker motor was expected to 
decrease the speed on the conveyor when 
the anti-stall switch was actuated. How- 
ever, power-consumption data (fig. 9) 
shows that current draw was high only for 
short periods of time, and the anti-stall 
feature was not activated for breaking 
single rocks. Figure 9 shows breaker 
operation during the trial C. 

TAIL-BOOM LIFTING 

The HFB was designed with a tail boom 
that is more sturdy than booms on exist- 
ing continuous miners to enable the HFB 
to perform either as a tractor or to 
support the inby end of continuous haul- 
age systems. To verify the support capa- 
bility, an 8,000-lb weight was lifted by 
the tail boom of the HFB. The weight 
was made by suspending a number of steel 
plates from a chain sling. Lifting tri- 
als were conducted with the HFB tail boom 
on the centerline of the HFB chassis and 
with the tail boom at maximum left and 
right swing positions (45° to the left 
and right of centerline). 



The HFB tail boom successfully lifted 
and held an 8,000-lb weight that was 
suspended from the tail boom, as shown 
in figure 10. No problems were observed 
when the tail boom suspended the weight 
with boom swings to the maximum left and 
right. 

COAL CONVEYING 

Coal-conveying trials were held to 
verify the surge-handling capability of 
the HFB and performance of the HFB 
chain-conveyor system. Surge capacity is 
essential if the HFB is used with con- 
tinuous haulage systems. To enable con- 
tinued HFB conveyor operation, the HFB 
was arranged in a closed-loop coal-con- 
veying circuit, as shown in figure 11. 
The circuit consisted of the HFB with 
bolter module removed, a 50-ft belt con- 
veyor, the 12-unit multiple-unit conveyor 
haulage (MUCH) system, and a 30-ft belt 
conveyor. 

To measure the discharge from the HFB, 
a belt weigh scale was installed on the 
50-ft belt conveyor, located immediately 
outby the HFB. The belt scale consisted 
of a speed sensor mounted on the belt 
tail pulley, a weigh bridge that provided 




FIGURE 10.— Tail-boom lifting trials. 



17 




FIGURE 11.— Coal-conveying trial configuration. 



an electric signal proportional to belt 
loading, and an electronic integrator 
and readout unit. Before commencing the 
coal-conveying trial, the belt scale was 
physically calibrated with calibration 
weigh chains. A strip-chart recorder was 
used to record the instantaneous belt- 
scale output during the coal-conveying 
trial. Recorder calibration was per- 
formed prior to each day's testing. At 
the beginning and end of each testing 
segment, the belt-scale totalizer dis- 
play was recorded to determine the total 
amount of coal transported. 

Testing commenced when a 1.5-yd -capac- 
ity front-end loader dumped coal into 
the HFB hopper, which discharged the coal 
onto the conveyor of the closed-loop sys- 
tem. The quick discharge of the front- 
end loader simulated surge loading by a 
continuous miner. Coal used during test- 
ing was wetted to control dust and con- 
sisted of a mixture of 2-1/2- by 2-in 
coal, 2- by 1-1/2-in coal, and run-of- 
mine coal from the Bureau's research 
mine. The coal was fed to the system 
until a system malfunction was detected. 

Table 5 is a summary of the discharge 
rate of the HFB over the entire trial. 
The maximum discharge rate was 6 st/min. 
Total operating time during the trial 
was 560.6 min. During the trial, a total 
of 682.1 st of coal was conveyed. The 
average discharge rate over the entire 



trial was 1.22 st/min, which was visually 
averaged from the chart recorder print- 
out for each run segment. During the 
test period, there were several HFB fail- 
ures: the main breaker tripped three 
times, the conveyor became jammed five 
times, and hydraulic failures occurred 
twice. Table 6 is a listing of HFB 
breakdowns during the trial. Since the 
coal being handled by the HFB during the 
trial was wetted to control dust, it is 
probable that the greater effort required 
to convey wetted coal increased hydraulic 
power requirements that contributed to 
all failures. Following the conveying 
trial, a cleanout hole was burned in the 
HFB chassis underneath the front conveyor 
idler to decrease the frequency of con- 
veyor jams; subsequent testing verified 
improved performance. 



TABLE 5. - Coal-co 
Average haulage 


nveying 
rate, 


trial 
T( 


summary 
sst time, 


st/min 
1-2 




min 

197.0 
244.2 


3 






65.0 


4 






23.9 


5 






29.0 








1.5 








560.6 



18 



TABLE 6. - Coal-conveying trial breakdown log 





Cumulative 


Average loading 




Date 


run time, 
min 


rate, st/min 


Description 


3/14/84 


18.0 


2 


Main breaker tripped out. Breaker was 
unable to be reset. Problem was diag- 
nosed as poor connection on source side 
of breaker. Connections were tightened, 
resolving the problem. 




50.0 


2 


Main breaker tripped out. Reason unknown. 
Breaker was reset. 




63.1 


2 


Power center tripped out. Reason unknown. 
Breaker was reset. 


3/29/84 


298.0 


2 


Main breaker tripped out. Problem was 
poor connection on load side of breaker. 
Breaker was overheated in that area. 
Connection was tightened, resolving the 
tripping problem. 


3/30/84 


341.0 


4 


Conveyor hydraulic motor hose failed. The 
crimp failed, allowing the hose to blow 
out end of fitting. The crimp-type, 
staple-lock fitting was replaced. 




341.5 


4 


HFB was jammed. Wet coal overloaded the 
conveyor system. Hopper was emptied 
manually. 




518.2 


3 


HFB was jammed. Ran conveyor back and 
forth to clear hopper. 


4/06/84 


525.7 


3 


HFB was jammed. Manually shoveled the 
system and ran conveyor back and forth to 
clear system. 




531.7 


4 


HFB was jammed. Manually shoveled the 
system and ran conveyor back and forth to 
clear system. Intermediate vehicle 1 
also stopped. Reason unknown. 


4/09/84 


552.2 


6 


Conveyor hydraulic motor hose blew out of 
crimp fitting. (This hose was on the 
opposite port to the hose, which failed 
on 3/30/84.) Hose was replaced. 


4/12/82 


554.2 


4 


HFB was jammed. Ran conveyor back and 
forth to clear system. 



19 



The HFB coal-conveying trials were con- 
ducted with a prototype continuous haul- 
age system, which limited the HFB evalu- 
ation. The HFB has a 4-3/4-st capacity 
hopper with a 28-in-wide by 8-in-deep 
variable speed conveyor that was designed 
to limit the discharge rate from the HFB 
to 6 st/min, even though the discharge 
rate of a continuous miner loading into 
the HFB may be much greater for short 
periods of time. During the trial, a 
6-st/min discharge rate was achieved for 
only 1.5 min out of the 560.6 min total 
test time. Lack of operating time at 
6 st/min is not due to a deficiency in 
the HFB, but rather to the performance 
of the HFB and MUCH coal-conveying test 
loop. It was observed that when the 
front-end loader discharged into the HFB 
hopper, the HFB did limit the discharge 
rate to below 6 st/min without spillage 
or clogging. 

DUST-COLLECTOR EVALUATION 

Initial examination of the HFB indi- 
cated that the primary dust-collector 
boxes were located in an undesirable 
location. The boxes, in their original 
position between the TRS cylinders on the 
bolter module, could only be opened by a 



person standing inby of the TRS. Various 
alternatives were evaluated, and a deci- 
sion was made to relocate the primary 
dust boxes midway on the bolter module 
boom (fig. 12). 

The original festooned method of sup- 
porting the hydraulic hoses and vacuum 
line was replaced with a takeup config- 
uration, and a larger bolt tray was 
installed. The modifications allowed 
proper functioning of the bolter mod- 
ule; tramming and steering capabilities 
were not affected. The bolter opera- 
tors believed that the increased bolt 
tray capacity would increase bolting 
efficiency. 

Airflow and vacuum pressures were mea- 
sured to evaluate the performance param- 
eters of the relocated dust-collection 
system. A vane anemometer was used to 
measure airflow in each drill head. The 
4-in-diam anemometer was sealed in the 
end of a bell-type reducer fitting that 
terminated in a 1-1/8-in square fitting 
that was seated firmly in the drill head. 
A vacuum gauge rated at to 30 in of 
mercury, set in a 1-1/8-in square fit- 
ting, was used to measure vacuum pressure 
at the drill head. Prior to the airflow 
measurements, all dust-collector boxes 
were completely cleaned, and flow-control 




FIGURE 12.— Relocated dust boxes. 



20 



valves were opened. Airflow and vacuum 
pressures at the drill head were recorded 
under various operating conditions. Vac- 
uum pressures between the vacuum pump and 
the secondary collection box were also 
recorded under varying conditions. 

Results of the airflow measurements are 
presented in table 7. Although airflow 
values exceeded the minimum MSHA-recom- 
mended values, this was expected, since 
only the location of the primary dust- 
collection boxes and not the schematic 
diagram of the system was changed. 

Drilling trials were conducted to ver- 
ify the performance of the modified 
system. Observations and timings were 
recorded as the left and right drills 
were operated simultaneously and indepen- 
dently. All dust-collection boxes were 
thoroughly cleaned prior to drilling. 
One-piece, 48-in-long drill steels were 
used to drill 42-in-deep holes. Each 
steel was fitted with a 1-3/8-in-diam 
carbide drill bit. Holes were drilled 
into concrete roof blocks in the MBTS. 
Ten 42-in-deep, 1-3/8-in-diam holes were 
drilled before the dust-collection sys- 
tem became clogged (approximately 35 
lineal ft of roof drilling). This is an 
increase over the 28 ft reported in 
the roof-bolting trials section of this 
report. The clog located in the dust 



hose immediately connected to the drill 
head was easily removed. The average 
drilling rate during these trials was 
2.25 ft/min. The dust-collection system 
functioned properly during both indepen- 
dent and simultaneous drilling 
operations. 

DRAWBAR PULL 

A drawbar pull test was conducted to 
measure the drawbar pull of the HFB and 
to observe how the electronically con- 
trolled tram system would respond to an 
overload situation. Drawbar pull pro- 
vides a measure of the power available 
for towing and tramming up a grade. 

The drawbar pull of the HFB chassis 
(with the hopper empty) was measured by 
pulling against a dynamometer, which was 
anchored to a 35-st mobile crane, as 
shown in figure 13. The dynamometer was 
attached to the HFB chassis by a two-leg 
sling chain, which was attached to clev- 
ises mounted directly behind each HFB 
crawler. The crane parking brakes were 
used to prevent the crane from moving. A 
videotape camera and recorder were used 
to record the dynamometer dial reading 
and HFB drive sprocket motion as the HFB 
tried to pull the mobile crane. 



TABLE 7. - Dust-collector airflow measurements 



Condition 



Measurement 



Right chuck open Vacuum in blocked left chuck = 3.4/in Hg; 

airflow in left chuck = 25 ft 3 /min. 

Left chuck open Vacuum in blocked right chuck = 3.4/in Hg; 

airflow in right chuck = 25 ft 3 /min. 

Right chuck blocked Vacuum in blocked left chuck = 12.0/in Hg; 

airflow in left chuck = 40 ft 3 /min. 

Left chuck blocked Vacuum in blocked right chuck = 11.9/in Hg; 

airflow in right chuck = 41.5 ft/min. 

Both chucks blocked Vacuum at pump inlet = 12.5/in Hg. 

Both chucks open Vacuum at pump inlet = 8.0/in Hg. 

Right chuck blocked Vacuum at pump inlet = 8.9/in Hg. 

Left chuck blocked Vacuum at pump inlet = 9.0/in Hg. 



21 




FIGURE 13.— Drawbar pull test. 



Prior to the drawbar pull test, the 
weight of the HFB chassis was measured 
by freely suspending the chassis from a 
50-st-capacity dynamometer, which was 
attached to the 35-st mobile crane. The 
observed weight of the HFB chassis was 
49,500 lb. The mechanical dynamometer 
had a resolution of ±500 lb and a fac- 
tory-stated accuracy of 1/2 pet of full 
scale. 

The drawbar pull produced by the HFB 
on a dry fly ash-clay floor was measured 
between 25,000 and 38,000 lb. Readings 
were recorded from the dynamometer dial 
as the crawlers continuously slipped and 
jerked forward on the floor over several 
minutes. Ruts approximately 2 in deep 
were dug into the floor during this 
period. The videotape of the sprocket 
motion revealed that continuous torque 
was not maintained by the drive sprocket; 
sprocket relaxation during jerking and 
after a crawler slip was apparent. The 
relaxation was caused by the character- 
istics of the tram control system. 

A second test was conducted with the 
floor thoroughly wetted. The drawbar 
pull produced by the HFB was measured 
between 30,000 and 32,000 lb during 
crawler slippage. A dynamometer reading 
of 24,000 lb was recorded during slippage 
of the right crawler only. A dynamometer 
reading of 24,000 lb was also recorded 
during slippage of the left crawler only. 



No breaker tripping or erratic opera- 
tion was observed during the drawbar 
pull tests. The drawbar pull strength of 
the HFB is typical for a crawler-mounted 
vehicle the same weight as the HFB. 

TRS LOAD MEASUREMENT 

The objectives of this test were to 
measure the total load that the TRS sys- 
tem exerted against the mine roof and to 
verify proper performance of the TRS sub- 
system. The function of the TRS was to 
provide temporary roof support and opera- 
tor protection during roof bolting. The 
TRS on the HFB consisted of two, two- 
stage hydraulic cylinders. The roof end 
of each cylinder terminated in two arms, 
each with a plate for roof contact. The 
TRS cylinders received hydraulic power 
from a gear pump located on the HFB chas- 
sis. The main system relief valve pro- 
tecting the pump was set at 2,250 psi. 
The pressure to the TRS cylinders was 
protected by a relief valve located 
between the two TRS cylinders. The con- 
tractor recommended a maximum relief 
valve setting of 1,000 psi. Figure 14 is 
a diagram of the TRS hydraulic circuit. 

The test configuration is shown in fig- 
ure 15. Three 50,000-lb compression load 
cells were attached to the underside 
of the miner bolter test-structure roof 
cart. A 4- by 8- by 1-in steel plate was 



22 



positioned below the load cells. The HFB 
bolter module was positioned under the 
roof cart so that the raised TRS arms 
would hold the steel plate against the 
load cell's contact points. A 5,000-psi 



o 



m 



J 1 



e 



TRS flow 
control 



Ur 



1777777711 



annular area-^ annular 



m2 
area 



VlUlllIt I 



EZZZZZZ7T 



3" 



L_J 

Maximum setting, 
1,000 psi 

-28.3- in2 bore area 
FIGURE 14.— TRS cylinder cross section. 



pressure transducer was located between 
the TRS cylinder's load-check valve and 
the flow-control valve to measure the 
hydraulic pressure supplied to the TRS 
cylinders. Bridge amplifiers were used 
to condition the load cells and pressure 
transducer signals. Data were recorded 
on a tape recorder. The data display was 
generated by a strip chart via tape play- 
back. Pretest physical calibrations were 
conducted for all transducers. 

Two load measurement tests were con- 
ducted. For both tests the HFB was 
started, and the TRS was hydraulically 
powered against the steel plate until 
the relief-valve pressure setting was 
reached. The TRS flow-control valve was 
then closed. The HFB hydraulic pump was 
shut off 5 min after the TRS was set. 
The TRS remained in contact with the 
steel plate for 30 min and was then 




FIGURE 15.— TRS load measurement test configuration. 



23 



lowered. Load cell and pressure trans- 
ducer outputs were recorded continuously 
during these tests. 

Test results are shown in table 8. 
Tests were conducted at two different 
hydraulic pressure relief settings. For 
the first test, the pressure at the 
relief-valve setting was 998 psi. The 
initial measured load at this pressure 
was 26,107 lb. The pressure measured by 
the transducer located between the TRS 
load-check valve and flow control dropped 
to psi after the flow-control valve was 
closed. The load measured 26 min later 
was 23,871 lb. For the second test, the 
pressure at the relief-valve setting was 
527 psi. The initial measured load at 
this pressure was 12,682 lb. The load 
measured 22-min later was 10,304 lb. The 
data indicate that the TRS can hold loads 
without major leak -off. 

TABLE 8. - TRS load-test summary 



Test 


Pres- 
sure, 


Load cell, lb 


Total 


number 


1 


2 


3 


force, 




psi 








lb 


1 


998 


11,445 


8,212 


6,450 


26,107 


il 

X • • • ♦ 





10,396 


7,309 


6,166 


23,871 


2 


527 


5,050 


4,265 


3,367 


12,682 


2 





4,071 


3,433 


2,800 


10,304 



26.67 min later. 

The load exerted by the TRS against the 
mine roof cannot be considered the capac- 
ity of the TRS. Should the roof exert 
a load greater than the set load, the 
pressure inside the TRS cylinder will 
increase until the cylinder fails. The 
cylinder has a pressure rating of 5,000 
psi that corresponds to a hydraulic 
capacity of 125,000 lb. 

NOISE SURVEY 

The objective of the noise survey was 
to evaluate the noise level at the HFB 
operator stations in various modes of 
operation. The noise survey was con- 
ducted for stationary and mobile opera- 
tion of the HFB. The stationary noise 
survey consisted of 14 measurement loca- 
tions, 4 geometries, and 2 operating 



modes. Figure 16 is a plan view of the 
HFB that defines the stationary measure- 
ment locations. The measurement geome- 
tries were 

bolter fully retracted and full left; 

bolter fully retracted and full right; 

bolter fully extended and full left; 

bolter fully extended and full right. 

The two operating modes were 

only pump operational; 

pump, conveyor, and breaker 
operational. 

A calibrated sound-level meter was used 
to measure sound levels. The microphone 
frequency response was set to frontal for 
all measurements. Octave band A weighted 
measurements were taken via the fil- 
ter set attached to the meter. The ini- 
tial set of measurements consisted of 
background levels with the unit 
nonope rational. 

A total of eight static tests were gen- 
erated for the staionary tests. Posi- 
tions 11, 12, 13, and 14 were at the 
operator stations of the bolter module 
and moved relative to the main body of 
the machine as the bolter boom was posi- 
tioned. Positions 5 and 7 also moved 
relative to boom position. 

For the stationary tests, background 
noise had no effect on the measured data, 
since the background noise levels were 
15 to 20 dB below measured noise lev- 
els. Positions 8 and 9 exceeded 90 dBA 
for operation of the machine in the pump- 
only mode. These measurements were 1 m 
from the side of the machine at a 1.2-m 
elevation. The 1-m distance was chosen 
because this would be the typical dis- 
tance at which an observer would be 
standing. The pump motor appeared to be 
the primary source of noise with the 
1-kHz octave band dominating. All other 
measurement locations were below 90 dBA 
for pump-only operation of the machine. 



24 




LEGEND 
• I Measurement position 
Positions I - 10- At 4 -ft elevation 
Positions 5~ 7- Move with bolter boom 
Positions l|-|4 : At 5-ft elevation 



A-WEIGHTED SOUND PRESSURE LEVELS, dB (RE 20 


flPd) 


Measure- 
ment 
position 


Octave band center frequency, Hz 


Overall, 


31.5 


63.0 


125.0 


250.0 


5000 


IK 


2K 


4K 


8K 


16 K 


20-20,000 Hz 


1 


20.7 


35.3 


53.6 


68.0 


67.4 


69.4 


71.6 


64.2 


470 


30.0 


75.7 


2 


23.0 


38.7 


52.9 


66.6 


64.0 


69.9 


71.6 


64.4 


46.8 


30.5 


74.6 


3 


24.3 


40.8 


56.2 


65.9 


68.5 


71.3 


73.4 


68.2 


48.5 


30.4 


76.5 


4 


25.0 


41.0 


56.5 


71.0 


72.6 


76.7 


72.5 


70.1 


52.0 


34.2 


80.4 


5 


23.5 


40.4 


55.8 


69.7 


71.3 


725 


72.2 


68.2 


51.4 


37.4 


77.5 


6 


23.2 


38.1 


53.1 


59.0 


69.0 


72.7 


71.3 


67.8 


49.0 


30.4 


76.0 


7 


22.5 


39.0 


53.5 


68.1 


7Z5 


78.0 


76.7 


72.3 


54.1 


38.4 


81.8 


8 


45.0 


45.3 


597 


726 


81.1 


88.5 


88.0 


842 


66.8 


50.2 


92.9 


9 


46.7 


45.5 


605 


778 


83.2 


90.3 


87.8 


83.2 


67.2 


51.6 


93.6 


10 


25.4 


41.8 


56.6 


73.6 


77.1 


83.2 


81.1 


78.6 


60.5 


42.4 


86.6 


II 


23.4 


41.3 


54.7 


70.3 


703 


74.1 


72.9 


69.7 


52.3 


34.7 


78.8 


12 


20.7 


39.6 


54.1 


68.8 


70.2 


73.7 


73.1 


68.2 


52.2 


32.9 


78.2 



FIGURE 16.— Typical sound-level data sheet. 



25 



Activation of the conveyor and breaker, 
in addition to the pump, resulted in 
positions 1, 4, 8, 9, and 10 being equal 
to or exceeding 90 dBA. The 1- and 2-kHz 
octave bandwidths dominated for these 
measurement locations. The bolter-opera- 
tor measurements locations did not exceed 
90 dBA. 

Pass-by noise measurements were con- 
ducted for the right and left sides of 
the HFB. These measurements were taken 
at a 1-m distance from the outermost edge 
of the machine. The sound-level meter 
had peak hold capability, which measured 
the overall weighted noise level recorded 
as the machine trammed past the observer. 
Elevation of the measurement was 1.2 m. 

Following the pass-by tests, the ac 
output of the sound-level meter was input 
to the HP spectrum analyzer. The ana- 
lyzer accumulated spectral data in the 
peak hold mode, which allowed qualifi- 
cation of the noise into the frequency 
domain as the machine trammed past the 
sound-level meter. The analyzer then 
generated a spectral plot of the X-Y 
recorder. 

Pass-by tests were conducted with the 
conveyor and breaker inoperative. The 
right side of the machine had a 97.5-dBA 
peak reading at 1 m for the pass-by; the 
left side had 89.7 dBA. Figure 17 shows 
the peak hold spectrum generated by the 
machine during the pass-by. The spectrum 
for the right side (17.4) shows that most 
of the noise is between 800 to 2,000 Hz, 
and correlates with the pump motor. The 
left-side (175) spectrum shows no domi- 
nating noise source, since the spectrum 
has no dominating peaks. 

The pump motor is a major noise source 
on the HFB. Several measurement loca- 
tions exceeded 90 dBA primarily from 
pump-motor noise. Most of the pump noise 
lies in the 1- and 1-kHz octave bands. 
Since MSHA uses exposure criteria to 
establish noise limits, ^ it is unlikely 
that an operator would be stationed con- 
tinuously (8 h) in areas around a machine 
that showed sound levels over 90 dBA, 
especially if the operator uses the radio 
remote control. 



100 




< 

CD 

•a 



LU 

> 

LU 



UJ 

CC 
13 
CO 
CO 
LU 

ce 

0_ 



o 
to 



12 3 4 5 
FREQUENCY, kHz 

FIGURE 17.— Right- and left-side passby noise spectrum. 

LIGHT SURVEY 

The objective of this test was to con- 
duct a light survey of the HFB to eval- 
uate incident light levels around the 
machine when used in an 18- by 6-ft 
entry. MSHA^ requires that the luminous 
intensity (surface brightness) of sur- 
faces in a miner's normal field of vision 
and of work areas required to be lighted 
be no less than 0.60 fL. 

All measurements were made at night 
with the HFB located 80 ft south of the 
north wall inside the test building. A 
Panlux electronic light meter was used 
to measure incident light at designated 
locations on an imaginary box over the 
machine. Two survey rods were used to 
locate measurement locations. The imagi- 
nary box was scaled to simulate an 18- by 
6-ft entry. 

MSHA has different requirements for 
illumination on different types of equip- 
ment. Since the HFB is a hybrid machine 
and has no distinct classification, mea- 
surements were taken as if the machine 



5 CFR Title 30.70.502. 



5 CFR Title 30.75.1719-1. 



26 



were a hopper feeder, and then as a 
bolter separately. When the chassis was 
considered as a hopper feeder, measure- 
ments were taken in a plane 10 ft forward 
of the front of the chassis and 5 ft to 
the rear. When the bolter module was 
considered a bolter, measurements were 
taken in planes 6 ft from the bolter- 
operator's station. Figure 18 shows mea- 
surement locations when the machine func- 
tioned as a hopper feeder. Figure 19 
shows the measurement locations when the 
machine was considered a bolter. The 
light meter was held parallel to imagi- 
nary planes for all measurements. 



Footcandle 



Light loss 
measurement factor (0.77) 



Reflectance of 
x underground >0.06 fL 
surface (0.04) 



Locotion 


Light, fc 


Tl 


1.0 


T2 


2.0 


T3 


3.2 


T4 


5.7 


T5 


1.3 


T6 


1.7 


T7 


5.0 


T8 


1.4 


T9 


15.0 


T 10 


2.8 


T II 


1.5 


T 12 


6.5 


T 13 


1.6 


T 14 


2.3 


T 15 


2.7 


TI6 


.8 


TI7 


2.6 


T 18 


ai 


7 19 


4.4 


T20 


.7 



•TI6 



•TI7 



'TI8 



•TI9 T20« 



TI5« 




FIGURE 1 8.— Top incident light measurements for the hopper 
feeder. T1 measurement location (6-ft elevation). 



BTIO BTIl BTI2 

• • • — 

BT7 BT8 BT9 

BT4 

4'T ' BT5 BT6 

BTI BT2 BT3 





12' 



FIGURE 19.— Top incident light measurements for the bolter. 
BT1 measurement location (6-ft elevation). 



Location 


Light, fc 


BTI 


0.3 


BT2 


.8 


BT3 


.45 


BT4 


1. 5 


BT5 


.9 


BT6 


1. 6 


BT7 


I.6 


BT8 


1. 2 


BT9 


2.5 


BTIO 


.95 


BTIl 


.8 


BTI2 


1. 8 



From this equation, the minimum allow- 
able incident light for the floor, ribs, 
and ceiling of a given entry size is 
equal to 2.0 fc. 

Figure 18 tabulates the incident light 
measurements when the machine is consid- 
ered a hopper feeder. Several of the 
readings are below 2 fc, but since no 
ceiling or physical walls were available 
for reflection, it is assumed that the 
lighting would be adequate underground. 

Figures 20 and 21 tabulate the incident 
light measurements when the machine is 
assumed to be a bolter. The bolter has 
insufficient light to meet MSHA require- 
ments; however, since the bolter will be 
operating next to a continuous miner with 
proper lighting, it is assumed that the 
work area would be lighted sufficiently. 

SHUTTLE-CAR LOADING TRIAL 

In some mining situations, it is possi- 
ble for the HFB (with the bolter module 
removed) to be directly loaded by a shut- 
tle car. To evaluate this configuration, 
the HFB was loaded by a National Mine 
Service Model MC36-24S shuttle car with 
an extra-wide chain conveyor and boom. 



B5 B6 B7 B8 



Bl 



£X^ 



B2 B3 
12'- 



Location 


Light, fc 


Right 


Left 


Bl 
B2 
B3 
B4 
B5 
B6 
B7 
B8 


0.7 
.6 

1.0 

1.4 
.8 

1.2 
.8 

1.7 


0.3 
.25 
.25 
.4 
.45 
.2 
.3 
.3 



B4 

H 



FIGURE 20.— Incident light measurements for the bolter sides. 
B1 measurement location (6-ft elevation). 



M'H 




Location 


Light, fc 


Front 


Rear 


Bl 

B2 

B3 

B4 

B5 

B6 


2.0 
3.7 

1. 7 
2.0 
2.7 

1. 6 


0.I5 
.1 

.15 
.1 
.1 
.1 



FIGURE 21 .—Incident light measurements for the bolter front 
and rear. B1 measurement location (6-ft elevation). 



27 



The shuttle car has an overall width of 
11 ft and a discharge conveyor width of 
5 ft, 6 in. The shuttle car was loaded 
with a mixture of coal and dirt; the 
shuttle-car boom was raised and centered 
over the HFB hopper. Figure 22 shows the 
relationship of the shuttle-car boom to 
the HFB during the loading trial. The 
HFB breaker and conveyor were started, 
and the shuttle-car operator activated 
the shuttle-car conveyor intermittently 
to minimize spillage at the front of the 
HFB hopper. During the trial, there was 
spillage over the sides and front of the 
HFB hopper (fig. 23). To make the units 
more compatible, it is recommended that 
the inby end of the HFB be modified to 
better interface with the discharge end 
of a shuttle car. 

SURFACE TEST SUMMARY 

Surface testing and evaluation indi- 
cates the HFB is worthy of an in-mine 
trial. Specific achievements derived 
from the surface test program are as 
follows : 

The HFB can be easily trammed using the 
radio remote control unit. The average 
tram rate when maneuvering through cross- 
cuts with the extended bolter module was 
77 ft/min. 

The HFB bolter units and the three- 
stage dust-collection system perform 
effectively. During a bolter evaluation, 
each unit drilled through 5,000 psi 
compressive-strength concrete mix without 
a problem. 

Time-study data were gathered when the 
HFB was operated in a simulated produc- 
tion mode with a two-pass continuous 
miner while advancing 24 ft with roof 
bolting and position changing. 

A plan for "in-place" entry position 
changing of the HFB and a continuous 
miner was established. Several time 
studies were conducted with this plan, 
and the average time required for an 
in-place position change was 3 min, 9s. 

The HFB was successful in breaking 
rocks up to 18 by 30 by 24-in. 



The HFB successfully held an 8,000-lb 
weight that was suspended from the tail 
boom. 

During a coal-conveying trial, the HFB 
loaded 680 st of coal during 560 min of 
operating time. There were 10 minor 
failures that could be partially attrib- 
uted to conveying wetted coal. The HFB 
discharge rate was always below 6 st/min. 

Airflow and performance measurements 
taken on the modified dust-collection 
system were consistent with MSHA recom- 
mendations. The primary dust-collector 
boxes have an approximate capacity to 
hold the dust produced from 35 lineal ft 
of 1-3/8-in-diam holes. 

The maximum drawbar pull of the HFB 
chassis was 38,000 lb on a dry, com- 
pacted, clay-fly ash floor; the maximum 
drawbar pull on wetted ground was 32,000 
lb. 

The TRS load tests determined that with 
relief pressures of 998 and 527 psi, the 
TRS-generated roof loads were 26,107 and 
12,682 lb, respectively. The TRS main- 
tained these loads effectively without 
major leak-off. 

Noise survey tests indicate that the 
major noise source on the HFB is the 
electric motor driving the main hydrau- 
lic pump. Noise levels measured at vari- 
ous operator positions while the machine 
was operated in different modes indi- 
cate that the HFB will comply with MSHA 
regulations. 

Light survey tests show that the HFB 
has adequate lighting to meet MSHA 
requirements if the chassis is consid- 
ered a hopper feeder. Lighting is inade- 
quate if the machine is considered a 
bolter; however, illumination may be ade- 
quate when the bolter module is located 
beside a continuous miner. The HFB is a 
hybrid machine with no distinct MSHA 
classification. 

The HFB can be operated as a hopper 
feeder, with the bolter module removed, 
inby of a continuous face haulage system. 



28 







FIGURE 22.— HFB shuttle-car loading trial. 








FIGURE 23.— Spillage during loading trial. 



REPAIRS AND MODIFICATIONS 



29 



Numerous repairs and modifications 
were made to the HFB to correct deficien- 
cies observed during surface testing: 

MINING PLANS 



Appendix B is a listing of major modifi- 
cations; the repairs are presented in 
appendix C. 



The HFB machine concept is adaptable to 
a variety of mining plans. It can bolt 
beside a two-pass continuous miner, load 
into either a continuous haulage system, 
or intermittent (shuttle-car) haulage 
system. 

There are substantial benefits using 
the HFB to bolt beside a two-pass contin- 
uous miner: Tram time between cuts is 
minimized because entry-to-entry place 
changes between the continuous miner and 
roof bolter are replaced with side-to- 
side equipment changes between the con- 
tinuous miner and HFB bolter module. 
Supervision of the face crew is improved, 
since the foreman can simultaneously 
observe both mining and bolting. 

There are several benefits to using 
the HFB as a surge car-breaker inby of a 
continuous haulage system: The HFB can 
level the instantaneous surges produced 
by the continuous miner, thereby allowing 
use of smaller sized continuous haulage 
systems; the HFB can support the inby end 
of the continuous haulage system, thereby 
allowing a faster miner place change and 
cleanup rate; and the breaker on the HFB 
eliminates jamming in the face haulage 
system and the need for a feeder-breaker 
on the section belt. 

HFB WITH TWO-PASS CONTINUOUS MINER 

The HFB can be used to bolt beside a 
two-pass continuous miner. Figure 24 
shows the configurations of the HFB and 
miner through 10-ft-deep right- (RH) and 
left-hand (LH) cuts. At the start of 
the RH cut, the HFB bolter was 10 ft 
from the face and 10 ft from the miner 
cutterhead. During a 10-ft-deep RH box 
cut, the bolter module places six roof 
bolts on the left side of the entry. 
At the completion of a RH cut, ventila- 
tion is advanced into the box cut, and 
the bolter module and continuous miner 
exchange places within the entry. During 
a 10-ft-deep LH open cut, the bolter 



module places six roof bolts on the right 
side of the entry. At the completion of 
a box and open-cut sequence, roof bolts 
are installed to within 10 ft of the 
face. An additional roof bolter should 
be kept on the section to bolt cross- 
cuts. Because of the difficulties in 
providing sufficient clean air for the 
bolter operators, 20-ft-deep cuts are not 
recommended. 




Start RH cut 






Complete RH cut Place change 

and 
advance ventilation 





'fi 

W 

11 ' 




Start LH cut Complete LH cut Place change 

and 
advance ventilation 

KEY 
— - Airflow 

~-~» Brattice 
'. Roof bolts 

FIGURE 24.— Face-equipment configuration for 10-ft cuts. 



30 



Mining rates for the HFB continuous 
miner system can be estimated by tabu- 
lating time-study data obtained during 
surface testing. Table 9 presents HFB 
rates for 8- and 12-ft bolter advances. 
Bolter-module activities were divided 
into three elements: drill and bolt, 
advance bolter module, and place change. 
The advance-bolter-module time (1 min, 43 
s) and the place-change time (3 min, 9 s) 
may not vary much for different mining 
conditions. However, drill-and-bolt time 
will vary depending on the roof-bolt type 
and drilling conditions. The drill-and- 
bolt time during surface testing was 
3 min, 12 s for 42-in-long, 1-3/8-diam 
mechanical roof bolts. However, under 
the same conditions, the drill-and-bolt 
time for an experienced underground crew 
can be as low as 2 min, 30 s assuming 
two bolts are installed simultaneously. 

7 Suboleski, S. C. (A. T. Massey Coal 
Co., Inc.). Private communication, 1986; 
available upon request from R. J. Evans, 
BuMines, Pittsburgh, PA, 2 pp. 

TABLE 9. - HFB mining rates 1 





Number 


of 


Time, 




events 


min:s 


8 -ft BOLTER-MODULE ADVANCE 




4 




12:48 


Advance bolter module . 


2 




3:26 




2 




6: 18 






Total 


22: 32 




2:49 






12-ft BOLTER-MODULE ADVANCE 




6 




19:12 


Advance bolter module . 


4 




6:52 




2 




6: 18 






Total 


32:22 




2:42 






Rates assume that 4 roof 


bol 


ts are 


installed across width of entry. 






Average event time is 3: 


12, 


from 


table 3. 






Average event time is 1: 


«, 


from 


table 3. 






Average event time 


is 3: 


09, 


from 



Therefore, a 12-ft advance could be com- 
pleted by an experienced crew in 9 min, 
not counting a "place change." Assuming 
the place change takes roughly 3 min, the 
12-ft advance for an experienced crew 
will take a total time of 12 min. 

Depending on the drilling condition, 
crew experience, and roof-bolt type, a 
table can be developed, as shown in table 
9, to aid in estimating productivity. 
For example, in table 9 a 12-ft face 
advance, as determined from surface test- 
ing, takes 32 min, 22 s. Assuming a 20- 
ft-wide entry, 6-ft-high roof, 4- by 4-in 
bolting pattern, approximately 2 ft/min 
drilling rate, 360-min production time- 
shift, 80-lb/ft 3 coal density and a 12- 
ft-deep cut, the following formula could 
be used to estimate run of mine (ROM) 
coal production using the HFB: 

360 min x 1 cut x 20- by 12- by 6-ft 



1 shift 32.4 min 

80-lb coal 

X = X 

ft 3 

640 st 

— ■ ■ ■ ■ • 

shift 



1 cut 



1 st 



2,000 lb 



(1) 



place-change time study. 



When using 12 min for a 12-ft deep cut, 
which represents the best time for an 
experienced crew, the estimated produc- 
tion derived using the above formula is 
1,728 st per shift. 

Other mining rates could be estimated 
by changing the equation variables. For 
example, changing the roof height to 4.5 
ft and keeping the other variables con- 
stant, ROM production can be estimated at 
480 st per shift. In using this formula, 
caution should be observed. This formula 
does not include the extra time required 
for place changing between entries and 
other mine-specific delays. 

The depths of cut for the continuous 
miner and bolter-module advance are 
related. Assuming that roof bolts are 
installed on 4-ft centers and the depth 
of cut is 10 ft, bolter-module advance 
will alternate between 8 and 12 ft. 



31 



Figure 25 shows a proposed mining plan 
for two-pass break-to-break mining with 
the HFB using 10-ft cuts. Tram time 
between entries is required only when 
an entry is driven the length of one 
breakthrough. 

Not all cuts can be easily bolted by 
the bolter module: The start of turnouts 
would be difficult to bolt because of 
limited room. It would also be ineffi- 
cient for the HFB to bolt the 10 ft of 
roof at the completion of an entry, 
because the HFB should be moved with the 
miner to allow mining in another entry. 
Areas that are difficult to bolt with the 
HFB will be bolted by a separate bolter 
maintained on the section. 

A minimum of four personnel is required 
for the HFB continuous miner face crew: 
a miner operator, an inside bolter opera- 
tor, an outside bolter operator, and an 
HFB chassis operator. Figure 26 shows 
the positions of all four operators 



during a LH miner cut. Figure 27 shows 
the positions during a RH miner cut. 
Appendix A more fully explains the 
positions and responsibilities of each 
machine operator during a box- and open- 
cut mining sequence. 

When the HFB is used to bolt beside 
a miner, the following mining plan is 
recommended: 

The maximum entry width with a 4-ft 
bolting pattern is 20 ft. The minimum 
entry width should be 18 ft. A 20-ft 
entry width should be maintained, if pos- 
sible, to maximize the bolter-operator's 
working area. 

The cut plan should be designed to keep 
the bolter operators in fresh air. The 
10-ft cut plan, shown in figure 26, is 
recommended. A staggered 20-ft cut plan 
is not recommended, since the bolter 
operators must work directly in return 
air. 




LEGEND 



2 Entry sequence 
CS Cut sequence 



Section 
belt Not to scale 

FIGURE 25.— Mining plan for 20-ft cuts. 



MSHA requires that face areas be rock- 
dusted to within 40 ft of the working 
faces. 8 Provisions should be made to 
incorporate rock dusting in the break-to- 
break cut and in-place change sequence. 

Panic-bar or other type emergency stop 
switches should be installed along both 
sides of the continuous miner from the 
cutterhead pivot point to the rear of the 
chassis for additional bolter-operator 
protection. 

A single-boom roof bolter should be 
available on the same section as the HFB. 
Turnouts will be difficult to bolt with 
the HFB. Also, the HFB should not be 
used to bolt extremely bad roof beside an 
operating miner. 

Because of the previously discussed 
bolter-operator hazards, the bolter oper- 
ators should be thoroughly trained to 
properly operate the bolter prior to pro- 
duction use. 

8 CFR Title 30 Part 75.402. 



32 




FIGURE 26.— Bolter module positioned for LH miner cut. 




FIGURE 27.— Bolter module positioned for RH miner cut. 



33 



An adequate supply of spare parts 
should be available at the mine site to 
minimize downtime. 

BOLTER-MODULE HAZARD ANALYSES 

Although productivity benefits are pos- 
sible by using the HFB to bolt beside a 
two-pass continuous miner, the operators 
may be exposed to more hazards than 
conventional roof-bolter operators. The 
hazards are primarily caused by the prox- 
imity of the HFB bolter operators to the 
operating continuous miner. Figure 28 
shows operator locations for the HFB 
bolting beside a two-pass continuous 
miner in a 20-ft-wide entry. The inside 
bolter operator must work in a 3-ft-wide 
area between the continuous miner and the 
bolter module. The outside bolter opera- 
tor must work in a 4-ft^wide area between 
the bolter module and the coal rib. Both 
bolter operators are typically located 
12 ft from the front of the continu- 
ous miner cutterhead. The following are 
potential bolter-operator hazards: 




/////A ^~ Right bolter- 
^Z^zli operator's station 

Walkway 

-Left.bolter- 
> operator s station 



rMiner cable hung 
on mine roof 



Roof bolts 
installed on 
4- ft centers 



FIGURE 28.— HFB operators' areas. 



1. Sideways continuous miner movement 

Although the inside bolter operator is 
within good view of the continuous miner 
operator, sideways movement of the con- 
tinuous miner during cutting could pinch 
the inside bolter operator between the 
miner and the bolter module. Miner move- 
ment could be caused by unintentional 
activation of the miner crawler controls 
causing the miner to pivot or by cutting 
hard material. Continuous miner cable 
handlers who are sometimes positioned 
between the continuous miner and the coal 
rib can avoid these hazards because they 
constantly watch the miner and its cable. 
The inside bolter operator must con- 
centrate on roof-bolting operations and 
therefore may not be aware of continuous 
miner movement. To minimize this hazard, 
panic-bar or other types of emergency 
stop switches could be installed along 
both sides of the continuous miner to 
de-energize the miner, should it come too 
close to the bolter operator. 



2. Unintentional bolter-module movement 

Unintentional activation or "sticking" 
of the solenoid-controlled bolter-module 
tram motor or rotary actuator could pinch 
the bolter operator between the bolter 
module and the miner or coal rib. This 
can be controlled by effective train- 
ing to assure proper positioning of the 
bolter operators during bolter-module 
tramming. The bolter-tram and rotary- 
actuator rates can also be reduced to 
slower safe speeds. 

3. High noise levels 

The bolter operators must work in a 
high-noise area; therefore, hearing pro- 
tection may be required to comply with 
MSHA standards. The high noise level 
limits the ability of the bolter opera- 
tors to hear noise generated by unstable 
roof and the ability of the face person- 
nel to communicate. 



34 



4. Projectiles 

Although it is unlikely, the bolter 
operators typically located 12 ft from 
the front of the continuous miner cutter- 
head could be struck by projectiles gen- 
erated by cutting operations. 

5. Ventilation 

The bolter operators will be subject to 
some of the dust generated by the contin- 
uous miner at the coal face. It is rec- 
ommended that dust respirators be worn by 
the bolter operators. 

6. Mine cable handling 

As shown in figure 29, bolting on the 
right side of the miner requires that the 
continuous miner trailing cable be sus- 
pended over the bolter module. The con- 
tinuous miner cable must be hung from the 
roof during every LH cut, which creates a 



potential for back injuries and electri- 
cal hazards. 

In the current bolter-module design, 
roof bolts are installed manually by 
two bolter operators. A future concept 
design can be envisioned that would fea- 
ture remotely controlled or completely 
automated roof control without the need 
for bolter operators to work near the 
face area. The design and evaluation 
of this future concept is not included 
within this scope of work. 

HFB WITH CONTINUOUS HAULAGE 

The HFB can be used with or without the 
bolter module as a surge-car-breaker inby 
of a continuous face haulage system. 
With the bolter module removed (fig. 29), 
the hopper feeder can be used in a con- 
ventional place-changing mine plan. The 
hopper feeder is compatible with a vari- 
ety of continuous face haulage systems. 




FIGURE 29.— Hopper feeder. 



35 



Miner operator 



Hopper -feeder operator 




FIGURE 30.— Hopper feeder used with MBC. 



'////////////////// //////////////////////// ////////////////////////////////////A 

Hopper-feeder tail boom- 



opper of inby MBC 
unit 




//////nii))/i/i////>//i///////////////n////////'i//jH////////////i/ii>i/i/ii 

3' takeup 

FIGURE 31.— Hopper feeder MBC interface. 

It can support the inby end of a haulage 
system, or it can operate independently 
of the haulage system. Figure 30 shows 
the hopper between a continuous miner and 
the Bureau's monorail bridge conveyor 
(MBC). Four face personnel would be 
required: a miner operator, a hopper- 
feeder operator, a cable handler, and a 
(MBC) continuous haulage operator. The 
tail boom of the hopper-feeder (fig. 31) 
can be used to support the inby end of a 
continuous haulage system. Takeup capa- 
bility between the two units would be 
required, since the two systems will 
most likely have different tramming 
rates. Figure 32 shows a mine plan for 
the hopper-feeder used with continuous 
haulage. 




Not to scale 



Section 
belt 



FIGURE 32.— HFB with continuous haulage. Numbers indicate 
cut sequence. 



CONCLUSIONS 



The HFB is a prototype multifunctional 
machine that was designed to increase 
productivity and improve safety by elimi- 
nating place changing between the contin- 
uous miner and the roof bolter. Exten- 
sive surface testing was conducted at the 
Bureau's METF to evaluate criteria and to 
identify and make necessary modifica- 
tions before making an underground trial. 
Numerous modifications were made to 
improve system performance and reliabil- 
ity during surface testing. Successful 



test results under simulated mine condi- 
tions indicate this innovative system has 
the potential to increase productivity by 
combining functions typically performed 
by a roof bolter, surge car, and feeder 
breaker. Mining plans were developed for 
a two-pass continuous miner and a contin- 
uous haulage system. An in-mine trial is 
scheduled to be conducted at an under- 
ground coal mine using the hopper-feeder 
(without the bolter) in conjunction with 
a continuous face haulage system. 



36 



APPENDIX A.—HFB DEPLOYMENT 

Figure A-l shows the operating sequences of the HFB beside a two-pass continuous 
miner (CM). 




tubing or '/ 
brattice-ft 

4 



Nv\\\v. 

cm; 



HFB 



B 



If. 



CM 



HFB 




Vh 



KEY 
1^ Unbolted roof • Inside bolter operator 

■ Miner operator A Outside bolter operator 

♦ HFB chassis operator 




HFB 



HFB 



HFB 



H 



FIGURE A.1— HFB deployment. 



37 



APPENDIX B.—HFB MODIFICATION SUMMARY 



Date Modification 

4/83 A variable flow-control valve was 

installed in parallel with the bolter 
module tram motor. 

4/83 The left inby light bracket was moved 
6 in farther outby on the chassis. 

5/83 A frame was installed to capture the 
bolter vacuum hoses. 

10/83 The inby edges of the hopper were 
trimmed back and stiffened. 



10/83 Belt "skirting" was installed under the 
inby edge of the hopper. 



11/83 Belt "skirting" was installed under the 
upper edge of the sideboards on the 
left side of the HFB. 

12/83 The bolter-module's hold-down bar was 
removed and cover plates were 
installed. 

1/84 The solenoid-controlled hydraulic valves 
for the bolter-module tram and bolter- 
module rotary actuator pilot circuits 
were relocated between the TRS cylin- 
ders (into the space previously occu- 
pied by the primary dust-collection 
boxes) . 

6/84 The bolt tray on the bolter module was 
enlarged from 20 by 56 in to 36 by 56 
in. An additional rack for storing 
bolts was added to the bolt tray. 

6/84 The primary dust-collection boxes were 
relocated to underhung positions 
beneath the bolt tray. 



6/84 The hydraulic hoses, vacuum hose, and 
control cable to the bolter module 
were rerouted for a takeup extension 
arrangement. 



Reason 

The valve was required to vary the 
bolter module tram rate. 



The light bracket interfered with 
boom traverse. 

The hoses would catch on bolter 
hardware during mast movement. 

This change would allow greater 
access to the hopper by a miner 
discharge boom. 

The skirting would keep material 
from accumulating on the exposed 
hydraulic components. 

The belting provided an effective 
guard for the breaker roller 
chain. 

Initial tests showed that the 
hold-down bar was not required. 



This relocation improved access to 
the numerous hydraulic valves on 
the bolter module. 



The increased area on the bolt 
tray was desirable for storage 
of extra supplies. 



The original positions of the pri- 
mary dust-collection boxes were 
between the TRS cylinders. This 
was undesirable since the door to 
the boxes was inby the TRS. 

The original festooned extension 
arrangement would not work with 
the relocated dust boxes. 



38 



Date 



Modification 



Reason 



1/85 A pressure-relief valve was installed 
in the TRS circuit. 



The valve was specified in the 
hydraulic schematic but never 
installed on the HFB. 



2/85 The two diagonally oriented fluorescent 
luminaires on the inby end of the 
bolter module were replaced with one 
horizontally oriented luminaire. 

2/85 The two sodium-vapor luminaries on the 
tail boom were changed from a vertical 
to a horizontal orientation. 



The existing power supply was 
insufficient to power two 
luminaires. 



The luminaire entry glands were 
prone to damage in the vertical 
orientation. 



6/85 The adjustable mercury tube overloads 
between the output side of the SCR 
controllers and the dc tram motors 
were adjusted to trip at 300 A dc. 



The initial setting for the right 
overload was 290 A dc. The ini- 
tial setting for the left over- 
load was greater than 350 A dc. 
The right overload caused fre- 
quent tripping of the main 
breaker. 



6/85 The valve of the shunt resistors con- 
nected across the line current trans- 
formers was decreased from an equiva- 
lent value of 83 D to 80 D. 



The change decreased the value of 
the feedback voltage supplied to 
the current trip and current 
limit logic circuits. This was 
required to eliminate frequent 
logic tripping in the tram con- 
trol circuit. 



8/85 The value of the capacitor (4 on ESD 

drawing No. 5152954) was changed from 
250° to 470° F. 



This change decreased the accel- 
eration rate of the acceleration 
ramp generator in the tram- 
control circuit, thereby decreas- 
ing current overshoot and resul- 
tant tripping. 



39 



APPENDIX C.—HFB REPAIR SUMMARY 



Date Modification 

4/83 The weld between the TRS hydraulic 

cylinder and the base of the TRS was 
rewelded. 



Reason 

The original weld cracked, causing 
hydraulic oil to leak from the 
TRS. 



5/83 The left bolter torque relief valve was 
replaced and relocated. 



6/83 A reversing SCR and three integrated 

circuit chips in tram logic cards were 
replaced. The pump motor power leads 
were retaped. 



The original relief valve was 
struck by the rotary actuator 
assembly. 

A ground short of one phase of the 
three-phase pump motor caused the 
voltage potential of the other 
two phases to increase. This 
increased potential caused the 
failure of the solid-state 
devices. 



10/83 The pipe nipple connecting the pump 

motor to the pump motor's junction box 
was replaced. 



The pump-motor's junction box 
broke from the pump motor. Only 
one set of threads on the pipe 
nipple was engaged into the pump 
motor. 



11/83 The return spring on the solenoid- 
controlled bolter tram-pilot circuit 
was replaced. 

5/84 A broken lead on the pulse transformer 
board of the left crawler-reversing 
SCR was repaired. 

12/84 The left bolter thrust cylinder was 
sent to Fletcher Co. and repaired. 



The valve would occasionally stick 
in the open position, requiring 
emergency shutdown of the HFB. 

The HFB would not tram. 



A pinhole leak was found in the 
intermediate cylinder. Oil would 
shoot out during cylinder 
retraction. 



5/85 Two 5/8-in-diam bolts that hold the 
bolter module boom onto the boom 
traverse bracket were replaced. 



The bolts failed during tramming 
in rough bottom conditions and 
caused the bolter module to tip 
over. 



11/85 The conveyor's flexible sideboards were 
replaced. 



The original sideboards were dam- 
aged by the addition of welded 
extensions. 



U.S. GOVERNMENT PRINTING OFFICE: 1988 — 505-016/80,010 



INT.-BU.OF MINES,PGH.,PA. 28634 



U.S. Department of the Interior 
Bureau of Mines— Prod, and Dtstr. 
Cochrane Mill Road 
P.O. Box 18070 

Pittsburgh, Pa. 15236 



AN EQUAL OPPORTUNITY EMPLOYER 



OFFICIAL BUSINESS 
PENALTY FOR PRIVATE USE, WOO 

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BINDERY INC. |S| 

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